Case Report Veterinarni Medicina, 53, 2008 (7): 392–395 Heinz body anaemia in two dogs after Catalan spring onion (“calcot”) ingestion: a case reports R. Guitart1, C. Mateu2, A. Lopez i Agullo3, J. Alberola1 1Autonomous University of Barcelona, Bellaterra, Spain 2Veterinary Hospital of the Maresme, Mataro, Spain 3Veterinary Services of Mataro, Mataro, Spain ABSTRACT: Catalan spring onions, or “calcots”, are a very popular kind of vegetables obtained by special agro- nomic practices that avoid photosynthesis and subsequent metabolism by the Allium cepa plants. They have been considered for more than a century harmless for pets, as pleasant odour and sweet taste differ so largely from any other onion that can be ingested by children and adults in huge quantities, up to ~3% body weight, without problems being observed. However, the organosulphur chemicals responsible for oxidative damage to canine red blood cells found in this plant species seem to remain present, as two dogs were confirmed to be poisoned after eating left-over “calcots”. Both patients presented haemolytic anaemia with Heinz body formation, and eccent- rocytosis. Veterinarians and owners should be aware of the dangers associated with this particular onion variety and type, as it is highly palatable to pets and no effective treatment is currently available. Keywords: Allium cepa; poisoning; organosulphur compounds; oxidative damage The onion (Allium cepa) is one of the oldest Catalan spring onion, locally and internationally crops. Native to Central Asia (Brown, 2002), on- known as “calcot”, is a variety of A. cepa known as ion and garlic (A. sativum) are probably the most Blanca Gran Tardana cultivated mainly in Catalonia well-known representatives of the genus and also (North East of Spain), under very strict conditions. of the Liliaceae family. Apart from their culinary It is planted, replanted and successively covered in uses – fresh, cooked or dehydrated – medicinal soil in order to prevent photosynthesis, so that the properties have been attributed to both since an- edible part remains white. The process is similar cient times (Brown, 2002; Arnault and Auger, 2006), to the production of white asparagus (Asparagus prompting in recent years an accurate chemical officinalis), another liliaceae, a fact that explains the analysis of the most characteristic active ingredi- differences between the organoleptic and chemical ents (Jones et al., 2004; Arnault and Auger, 2006; composition of the white and green types of this Lanzotti, 2006; Santas et al., 2008). Nevertheless, vegetable (Rodriguez et al., 2005). The “calcot” is ingestion of onion and other Allium sp. are known collected young, before the plant fully develops, to be toxic to many animal species, including dogs, and is 15–25 cm long and 1.7–2.5 cm diameter cats, cattle, horses, sheep and goats (Talcott, 2004; in the edible stem (onion bulb not yet present), Sebastian, 2007). Although the dog appears to be which makes its shape similar to a green onion, but one of the most susceptible species (Sebastian, with a distinctive colour and flavour. The texture 2007), there are very few reports in the scientific is pleasant and tender, and the taste surprisingly literature concerning accidental canine poisoning sweet, very different from the strong odour and associated with onion ingestion (Stallbaumer, 1981; taste of any other known onion. Those produced in Kay, 1983; Fenwick and Hanley, 1985; Houston and Valls (Tarragona, Catalonia) have been honoured Myers, 1993), most of them being anecdotic. with the European Union Protected Geographical 392 Veterinarni Medicina, 53, 2008 (7): 392–395 Case Report Indication “Calcot de Valls” (European Commission, 2002), considering it a “fruit” (and not a vegetable), and are subject to active research (Laso et al., 2005; Santas et al., 2008). The most traditional way of eating “calcots” is in popular gastronomical fiestas known as “calco- tades”, where they are massively consumed after being roasted on open fires. Introduced in the late XIX Century, there are currently some 300 000 big “calcotades” every year in Catalonia, and they have become an important tourist attraction during the winter and spring seasons. There are contests where winners eat around 2.8–3.0 kg of “calcots” in one sitting, demonstrating that they are devoid of Figure 1. Blood smear (new methylene blue stain, × 1 000) toxicity for human beings even at very high doses. showing widespread Heinz bodies in erythrocytes Children are also active fellow diners, a fact that could erroneously induce us to believe that these confirmed regenerative normochromic macrocytic vegetables can be equally safe for pets. anaemia, with presence of abundant Heinz bodies, some eccentrocytes, and no parasites. Urine was normal, without haemoglobinuria. During the fol- CASE HISTORIES lowing days, Hct recovered up to 35%. Appearance of the animal improved, and finally the dog made Case 1 an uneventful total recovery, with no further clini- cal signs to date. A 14-month-old 4.2 kg female smooth-haired Dachshund was presented to a Veterinary Clinic in Mataro (Barcelona, Catalonia) with a history of Case 2 dark coloured urine and anorexia. The owners re- ported that the day before the dog ate an unknown, A 9-year-old 38 kg female Siberian husky was ad- but presumably quite large, quantity of “calcots”. mitted to a Veterinary Hospital in Mataro because the Initial physical examination confirmed very dark dog had refused food for the last three days and was and turbid urine, though other urine analysis pa- apathetic and depressed. According to the owners, the rameters were normal. Haematocrit (Hct) value was animal had ingested the left-overs of a “calcotada” six 40.7% (reference range 37–55) and haemoglobin days before; the amount of onions consumed could (Hgb) 12.7 g/dl (reference range 12–18). The fol- not be quantified and, moreover, part of them was lowing day, Hct decreased to 38%, although urine eliminated later by non-induced vomits. was slightly less dark. Upon arrival at the clinic early in the morning, Four days later, anorexia worsened, 2–3 vomits the dog was examined and samples of blood with- occurred, and pale mucous membranes and ab- drawn for analysis. Hct was 15.4%, Hgb 5.9 g/dl, dominal gases were observed. Ecography revealed RBC 1.86 × 106/μl and MCV 82.8 fl. Potassium moderate splenomegaly. Hct was 24.7%, Hgb 7.0 g/l, was 2.9 mmol/l (reference range 4.4–6.1), with all and platelet count 735 × 109/l (reference range other parameters analyzed normal. Infection with 175 × 109–500 × 109). Urea and creatinine were Ehrlichia canis, Dirofilaria inmitis and Borrelia well below the normal range. Cimetidine (Tagamet, bugdoferi was serologically discarded. With the GlaxoSmithKline) and, to control vomits, meto- recent experience of the previously described case, clopramide (Primperan, Sanofi-Synthelabo), were the hospital makes a rapid tentative diagnostic of administered. hyperchromic macrocytic anaemia induced by “cal- The next day, Hct increased slightly to 26.3%, cot” ingestion. A Ringer lactate supplemented ini- with red blood cell (RBC) count 3.06 × 106/μl (ref- tially with potassium chloride infusion and oxygen erence range 5.61–7.46) and mean corpuscular therapy was provided. A broad spectrum antibiotic, volume (MCV) 85.9 fl (reference range 65–80). ampicillin (Nuvapen, Reig Jofré) at 15 mg/kg tid, Supravital staining of a blood sample (Figure 1) was also administered for three days. 393 Case Report Veterinarni Medicina, 53, 2008 (7): 392–395 The day after admission, a transfusion of packed ered and proposed as causative agents, either in red blood cells (PRBC) was initiated at 01:00 a.m. onion (Munday et al., 2003) or in garlic (Yamato At 4:45 a.m., Hct was 23%, and at 09:00 a.m., 21.2%, et al., 2003) poisoning episodes. The susceptibility with Hgb 7.9 g/dl, RBC 2.72 × 106/μl, MCV 77.9 fl to onion intoxication depends on several factors and potassium 3.9 mmol/l. Urinanalysis was normal. (Talcott, 2004), the hereditary condition result- Supravital staining of a blood sample confirmed the ing in erythrocytes with high concentrations of presence of abundant Heinz bodies, some eccentro- reduced glutathione and potassium probably be- cytes, and no parasites. Discarding other potential ing the most studied (Yamato and Maede, 1992; causes for the haemolytic anaemia, a confirmed di- Yamato et al., 1999). agnosis of “calcot” poisoning was established. The special farming technique applied to “calcots” In the following two days, Hct recovered to 25.2% modifies their chemical composition. It has been and 27.2%, with the other haematological param- shown that, compared to other onions, it reduces eters also showing a trend to return to normality. their content in flavonoids, a group of polyphenolic The dog was discharged after 72 hours of hospitali- compounds with antioxidant activity (Santas et al., zation. Vitamin E (Auxina E; Chiesi-Espana) 400 UI 2008), probably in a similar way to what occurs to bid was prescribed, and subsequent clinical exami- white asparagus (Rodriguez et al., 2005). According nation revealed no further problems. to their differential flavour, pungency and odour – characteristics known to be associated with orga- nosulphur compounds (Jones et al., 2004; Lanzotti, DISCUSSION 2006) – “calcots” also probably contain lower, but still significant, levels of these toxins. Ingestion of onions has been associated with Several therapeutic approaches have been sug- haemolytic anaemia accompanied by the formation gested to treat onion-poisoned animals, including of Heinz bodies (Talcott, 2004; Sebastian, 2007). gastrointestinal decontamination, administration Eccentrocytes can also be observed, but are seen of antioxidant vitamins (C and E) or N-acetyl- in higher proportion after garlic ingestion (Lee et cysteine, and intravenous fluid therapy or blood al., 2000). Both haematological damages are indica- transfusions (Kay, 1983; Gault et al., 1995; Hill et tive of oxidative injury, although in experimental al., 2001; Talcott, 2004), but none has been prov- studies the increase of methaemoglobin was of no en really effective.